645742636 has 48 divisors (see below), whose sum is σ = 1420618752. Its totient is φ = 251573520.

The previous prime is 645742633. The next prime is 645742651. The reversal of 645742636 is 636247546.

It is a junction number, because it is equal to n+sod(n) for n = 645742592 and 645742601.

It is not an unprimeable number, because it can be changed into a prime (645742633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28605 + ... + 45931.

It is an arithmetic number, because the mean of its divisors is an integer number (29596224).

Almost surely, 2^645742636 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645742636, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (710309376).

645742636 is an abundant number, since it is smaller than the sum of its proper divisors (774876116).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645742636 is a wasteful number, since it uses less digits than its factorization.

645742636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17371 (or 17347 counting only the distinct ones).

The product of its digits is 725760, while the sum is 43.

The square root of 645742636 is about 25411.4666243411. The cubic root of 645742636 is about 864.3437329017.

The spelling of 645742636 in words is "six hundred forty-five million, seven hundred forty-two thousand, six hundred thirty-six".